This invention relates generally to heavy duty transport vehicles for carrying loads on conventional roadways and, more specifically, to a heavy load hauling vehicle for moving medium to massive loads such as heavy equipment or the like which includes a front, tractor-drawn carriage or jeep, a rear carriage or jeep and a load unit disposed between and supported by the carriages.
Multi-axle, semitrailer-type transport vehicles are known in the prior art and are well represented by the following U.S. Pat. Nos.: 2,819,911; 3,903,979; 3,968,495; 3,689,107; 3,690,698; 3,734,538; 3,930,669; and 4,165,005. The transport vehicle of the present invention is directed to providing adjustable or variable loading on components of the vehicle and to carrying substantially heavier loads than the vehicles disclosed in these patents.
There are numerous patents disclosing improvements to trailer-type transport vehicles and components thereof. Stabilizing or adjustable fifth-wheel hitches are known and generally provide sway or tilt features or mechanisms for accommodating relative motion between a towing vehicle and a trailing vehicle. Representative patents include U.S. Pat. Nos. 3,122,382; 3,309,111; 4,199,168; and 4,444,408. Once again, however, the improvements disclosed in these patents are directed to working with substantially lighter loads than is the present invention; variable or adjustable loading of overall vehicle components is not addressed.
Vehicles for carrying very heavy loads and components therefore are disclosed in U.S. Pat. Nos. 4,453,734; 4,460,194; 4,468,048; 3,438,652 and 3,439,630. These patents disclose various suspension systems for wheel/axle units or articulated two-part carriages. Controllable steering for trailer-type vehicles for hauling heavy loads is disclosed in U.S. Pat. No. 4,468,047 and fifth-wheel couplings are also disclosed. U.S. Pat. No. 3,393,758 discloses a mechanism for widening the distance between crawler frames of a crawler-type vehicle.
Despite the advancements and improvements in the art concerning heavy duty transport vehicles, there still are some significant problems, particularly when intended payloads approach the one million pound level. These difficulties include: achieving optimum distribution of the load evenly among the wheels; achieving a soft ride so that the extremely heavy rolling loads do not damage the road surfaces, the load or the vehicle itself; achieving a stiff ride in a direction transverse to the travel direction so as to give optimum stability to the traveling load; and, conforming to different standards of weight bearing and weight distribution for vehicles making use of roadways under the various jurisdictions that might be encountered during a long distance trip.
The co-inventor of the present invention, James McGhie, is the inventor or co-inventor of a number of the above cited patents. He is also the co-inventor of pending U.S. Pat. Application Ser. No. 187,557, filed Apr. 28, 1988. That application is directed to providing a heavy load hauler having hydraulically suspended, steerable, independent wheel and axle units in an attempt to address some of the previously noted difficulties in transporting heavy loads. The present invention is directed to further improvements to heavy duty transport vehicles for transporting medium to massive loads.